so i have a 2008 jeep patriot with 99k miles on it already. Ive had the back brakes done twice as of this last weekend but the front brakes are still what the car came with. The shop keeps telling me that they are fine and that it has to do with how i drive that they dont wear out as quick as the back ones. The front are disc brakes, whereas the back are drum brakes. So does this sound normal?